In such a prior art differential amplifier which is driven asymmetrically, the emitter electrode of the first transistor is controlled by means of the base input voltage, and half of this control voltage is produced at the point in which the emitter resistors are connected to the current source; approximately the same alternating voltage is also produced at the emitter of the transistor which is not controlled via its base. Stray capacitances are usually operative at the said circuit points and in combination with the neighbouring impedances, particularly the emitter resistors and the transistor internal resistances, a low-pass effect is obtained from the first to the second transistor in such manner that higher frequencies are only transmitted in an attenuated manner. The second transistor is then driven with only a limited frequency, so that the frequency band of the signals taken from the output point of the two differential amplifier transistors is limited, and the signals are possibly not sufficiently symmetrical.
The invention has for its object to reduce to a considerable extent the narrowing down of the frequency band when higher frequencies are amplified.